Method of and apparatus for rolling flat strip



Aug. 5,1969 M. o. STONE METHOD OF AND APPARATUS FOR ROLLING FLAT STRIP Filed Sept. 1, 1966 IN\-'ENTOR. MGR/W5 .0. STONE ATTORNEK United States Patent US. C]. 72-12 7 Claims ABSTRACT OF THE DISCLOSURE The present invention relates to a method of and apparatus for producing flat metallic strip or sheets, and more particularly, to the production of such characterized material incident to a rolling operation. The method disclosed includes the steps of forming a tension zone after the strip leaves the mill followed by a nontension zone, in which zone the degree of flatness is ascertained and after which the tension in the tension zone is varied in addition to varying the contour of the rolls to control the tension influence during rolling.

Cross reference to related application This application is based on a British provisional, Ser. No. 39,052/65 dated Sept. 13, 1965, for which application the applicant is claiming a right of priority pursuant to 35 U.S.=C. 119 of the Patent Act.

Many users of flat rolled sheet and strip material are requiring that the sheet or strip possess a certain minimum quality of flatnes. By flatness it is meant the ability of the material to lie flat on a horizontal plane as distinguished from the thickness of the material. Thus, the quality of flatness relates to the absence of irregular ities such as waves or buckles. While a number of designs and methods of operation have been developed in an attempt to obtain flat strip and sheets, prior designs and methods have not had sufficient flatness capacity and were faced with the disadvantage of not being able to discern the flatness condition of the strip so that the correct procedure for removing the non-flatness could be initiated. Thus far, to a great extent, the correct flatness procedure has been a matter of trial and error which has not proven satisfactory, nor does it appear that there is any hope of such procedure meeting the present demand nor of the anticipated more stringent requirements relative to strip flatness.

As indicated, the present invention relates to a method of and apparatus for processing strip and sheet material in a manner in which sufficient flatness capacity is assured and in addition the non-flatness of the strip can be ascertained and the corrective measures taken both during the rolling operation.

More specifically, the present invention provides a method of and apparatus for detecting the non-flat conrlition of strip or sheets as it leaves a rolling mill and should the flatness quality =be objectionable, either varying the tension distribution across the width of the material at the bite of the mill or controlling the configuration of pass opening of the mill or combining these two variables, thereby to correct for a non-flat condition of the material and maintain the material in the flat condition.

An apparatus for carrying out the method in a preferred arrangement may include in spaced sequential arrangement a strip payoff reel, a first tension bridle, a first variable crown controlled strip deflector roll, a

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first 4-high reduction mill, a second 2-high or 4-high mill, 2. second variable crown controlled strip deflector roll, second and third tension bridles arranged to form a strip no-tension zone, and a tension reel to wind up the strip.

It will be appreciated in a given case that only one mill need be employed and the mills need not be 4-high mills and further, that one set of bridles and one deflector roll need not be employed without departing from the scope of the invention.

Drawings It is believed that the aforesaid objects and advantages of the present invention will be better understood when the following description is read along with the accompanying drawing of which:

FIGURE 1 illustrates schematically one form of the present invention employed in conjunction with a tandum 4-high cold reduction mill arrangement.

FIGURE 2 illustrates schematically a second form of the present invention employed in conjunction with a single stand rolling mill,

FIGURE 3 is a schematic view of a third form of the present invention, and

FIGURE 3a illustrates one form of a variable deflector roll shown in FIGURES 1 and 3.

Description of invention With reference to FIGURE 1 of the drawing there is shown in sequential spaced-apart relationship from left to right as one views the drawing, a payoff reel 11 on which a coil 12 of metallic strip S has been placed and a portion thereof fed to and through the mill, yet to be described. Following the payoff reel 11 there is provided a first tension bridle 13 consisting of two vertically arranged rolls 14 and 15 over which the strip S is passed and by which means a tension is maintained between the payoff reel 11 and the tension bridle 13.

On one adjacent side of the tension bridle 13 directly across from its rollers 14 but spaced therefrom is a variable crown controlled strip deflector roll 19 which is identified as such by a legend in FIGURE 1. This roll is more fully illustrated in FIGURE 3a and is provided with means at its ends to impose bending moments on the roll thereby to deflect its central portion that is in contact with the strip S. A more detailed explanation of the construction of the deflector roll 19 is contained in US. Patent No. 3,328,992 which issued July 4, 1968. As the drawing shows, the relationship of the strip passing to the deflector roll 19 from the tension bridle 13 is such that the underneath side of the strip is caused to encircle an appreciable portion of the periphery of the roll 19. In this way suflicient contact is maintained between the strip and roll so that the variable controlled contours of the roll 19 subject the strip to variable tension distributions across its width.

On the delivery side of the deflector roll 19, there is provided the first of two 4-high rolling mills 21. This mill 21 consists of a pair of work rolls 22 each of which are backed up by backup rolls 23 according to wellknown rolling mill design. As indicated in FIGURE 1, associated with the backup rolls 23 of the mill 21 there are provided hydro-mechanical variable crown control devices, for example, of the type set forth in British patent specification No. 870,777 granted June 7, 1961. The illustrated crown control device includes a yoke 24 received on extended neck portions of each backup roll 23. Arranged between these yokes are two force exerting means 25 in the form of pistons 26 and cylinders 27. It will be appreciated that while backup crown control devices have been provided for the mill 21, the

work rolls 22 thereof can be subject to hydro-mechanical crown control, which devices are well known in the industry.

Following the mill 21 and spaced therefrom there is a second rolling mill 28 consisting of a pair of work rolls 29, each backed up and supported by backup rolls 21. As indicated in FIGURE 1, this mill also has hydro-mechanical crown control devices for the backup rolls 31 which devices include yokcs 32 received on extended neck portions of each backup roll 31. Two force exerting means 33 in the form of pistons 34 and cylinders 35 operatively engage each of the yokes 32. Although as previously mentioned, such control could be provided for the work rolls 29 or alternately, for example, the mill 21 could have backup roll crown control and a work roll crown control provided for the mill 28. Following the second mill 28, there is provided, as identified by the legend, a second variable crown control strip deflector roll 36 similar in construction and operation to the deflector roll 19 previously mentioned and to be more fully described hereinafter. On the delivery side of the deflector roll 36, there is provided a second tension bridle 37 constructed similar to the bridle 13 comprising two vertically spaced rolls 38 and 39 which are operated so as to impose a tension between the bridle 37 and the mill 28 in a manner that the strip S is caused to forcefully encircle the deflector roll 36.

Continuing to move from left to right as one views FIGURE 1, spaced from the bridle 37 is a third bridle 41 comprising two vertically arranged rolls 42 and 43, the bridles 37 and 41 being so arranged that a no-tension zone is provided between them. At the delivery side of the bridle 41 there is provided a tension windup reel 44 on which a partial coil 45 has been formed.

With reference to the equipment that has just been described and in referring again to FIGURE 1, it will be noted that the various areas between the various equipment have been identified as zones as follows: the area between the payoff reel 11 and tension bridle 13 as zone A; the area between tension bridle 13 and the mill 21 as zone B; the area between the two mills 21 and 28 as zone C; the area between the mill 28 and the tension bridle 37 as zone D; the area between the two tension bridles 37 and 41 as zone E; and finally, the area between the tension bridle 41 and the tension reel 44 as zone F.

FIGURE 1 also illustrates schematically fluid control lines 46, 47, 48 and 49 that are respectively connected to the roll bending means of the deflector roll 19, the force exerting means and 33 of the roll bending means of the rolling mills 21 and 28 and the roll bending means of the deflector roll 36. The lines 46, 47, 48 and 49 are supplied with fluid pressure from a pump 51 through a pressure control 52 which in its simplest form comprises a separate pressure control valve for each line.

With reference to the method and apparatus herein disclosed, a practical example of a rolling mill process incoporating the features of the invention will now be given.

Let it be assumed that the strip S is a low carbon strip having a carbon content of .10 with a width of 40", in which its entering gauge at the mill 21 is .010 and its delivery gauge from the mill 28 is .007. As to the reductions taken in the mills 21 and 28, in the mill 21 the strip is reduced from .010 to .0075 and in the mill 28 the strip is finally reduced from .0075 to .007. The tension condition in the various zones A to F is as follows: Zone A3,000 lbs. per square inch total tension; zone B-7,000 lbs. per square inch total tension; zone C-10,000 lbs. per square inch total tension; zone D5,000 lbs. per square inch total tension; zone Ezero tension; and finally, zone F-2,500 lbs. per square inch total tension.

With these characteristics in mind, in the operation of the illustrated equipment the strip S is fed through the various zones A to F and started on the reel 44. The mills 21 and 28 will then be brought up to their operating speeds in the usual way, in which regard the flatness condition of the strip will be inspected in zone B. Depending on the flatness characteristic of the strip in this zone, the operation will actuate the control 52 to regulate the variable crowns of either or both of the deflector rolls 19 and 36 and supplementary or alternatively thereto will regulate the mechanical crown control provided for the backup rolls 23 and 31 of the mills 21 and 28, respectively. The mechanical crown control provided for the mill 21 will be so regulated to compensate for the inherent roll deflections of the rolls due to the rolling loads, thereby avoiding any appreciable differential rolling loads across the opening between the rolls 22 and 23.

With respect to the operation of the mill 28 and the deflector roll 37, operation of these two units may be similar to that just discussed with respect to the mill 21 and the deflector 19, if this additional flatness capacity is needed. It will be appreciated that the zone for detecting the flatness characteristic of the material will be in the zone E, since when the strip reaches this zone the rolling action has already taken place and the change necessary to correct for flatness can be anticipated and the necessary adjustment made to the crown control equipment.

In the event it is desired to provide a fully automatic flatness detecting arrangement, a light energy non-flatness detector can be provided, such a devise also being shown schematically in FIGURE 1. This device has a light admitting source 53 arranged at an angle to play upon the upper surface of the strip whereby the light rays hit the strip at an angle and are deflected off into a receiver 54. In this connection the degree and character of light rays received by the receiver 54 determine the magnitude of the waves or non-flatness of the material. In a given case depending on the width of the material a number of these units can be spaced along the surface, both transversely and longitudinally of the strip, thereby detecting the flatness condition at various points and in two opposite directions within the no-tension zone E. Once the electrical signal is produced representative of the non-flatness condition of the material, the mechanical crown control mechanisms can be automatically operated to correct for the non-flatness of the material by feeding such a signal into the pressure control 52 which will be adapted to automatic operation.

Still another non-flatness detecting device is illustrated in US. Patent No. 3,161,824 issued on Dec. 15, 1964, to H. E. Brys.

With reference now to FIGURE 2, which, is previously indicated, represents a second embodiment of the present invention, there is provided in a spaced sequential arrangement, a payoff reel 55 for uncoiling a strip 56 for feeding into a rolling mill 57, which is constructed in accordance with well-known practice, and includes a backup roll crown control device 58. A specific description of the crown control device will not be given in this instance since it is to be appreciated that this device is identical to the crown control device illustrated with respect to the rolling mills 21 and 28 of FIGURE 1. Passing from the rolling mill 57, there is provided a reel 59 on which the strip is coiled to form a coil 61. In the embodiment the reel 59 will be operated so as to form a substantially zero tension loop zone between the rolling mill 57 and the reel 59. In this zone strip unflatness is detected and the backup crown control actuated in accordance with the detected degree of non-flatness.

Turning now to FIGURE 3, which represents a third embodiment of the present invention, there is arranged in a spaced sequential arrangement a payoff tension reel 62 which feeds a coil 63 for issuing strip under tension over a variable crown control strip deflector roll 64 to a rolling mill 65. From the mill the strip passes to a reel 66 on which the strip is formed into a coil 67. The relative speeds between the rolling mill 65 and the reel 66 are so controlled that a substantially zero tension loop zone is formed between them where strip non-flatness is detected. The detected degree of non-flatness is then employed to diflerentially vary the tension transversely of the strip entering the rolling mill by employing the variable crown control defiector roll 64. As illustrated in FIGURE 3a, a deflector roll 64, as well as the deflector rolls 19 and 36 of FIGURE 1, comprises extending roll journals 68 on which there is received inboard bearing assemblies 69 and outboard bearing assemblies 71. The inboard bearing assemblies 69 are rigidly secured to the foundation while the outboard bearing assemblies 71 are each secured to roll bending piston cylinder assemblies 72 which receive fluid under pressure from a line 73. Operation of the piston cylinder assemblies 72 imposes deflection forces upon the roll 64 to deflect the roll about its longitudinal axis in a manner to impose greater tension stresses in one or more transverse portions or the strip in contact with the roll, than in other portions of the strip.

While the present invention has been explained with reference to the process of cold reducing strip, it will be appreciated that it can just as conveniently be used in temper rolling or the rolling of hot strip and that it can also be used in the processing of non-ferrous metals.

In accordance with the previsions of the patent statutes, I have explained the principle and operation of my invention and have illustrated and described what I consider to represent the best embodiment thereof. However, I desire to have it understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

I claim:

1. In a method of controlling the flatness characteristic of metallic strip by subjecting the strip to rolling pressure created by a pair of rolls of a rolling mill or like device, comprising the steps of:

creating a first strip tension zone wherein immediately prior to the strip entering into the mill the strip is subject to tension,

reducing the thickness of the strip by rolling,

creating a second strip tension zone wherein immediately after the strip leaves the mill the strip is subject to tension,

forming a relative no-tension zone after said second tension zone wherein the strip is substantially free from tension,

detecting the degree of non-flatness possessed by the strip in the no-tension zone,

selectively varying in a controlled manner the tension transversely of the strip in said first and second tension Zone, and, in addition, varying in a controlled manner the contour of the pass opening of the mill,

thereby the controlled strip tensions and controlled contour pass opening subject the strip to differential transverse rolling pressures that correct for the nonflatness of the strip.

2. In an apparatus for producing flat strip comprising:

a rolling mill having a pair of rolls between which strip is rolled,

means for varying in a controlled manner the rolling pressure transversely of the strip,

means for forming a zone on the delivery side of said mill for maintaining said strip in a state relatively free of tension, said zone forming means arranged to receive the rolled strip from said mill,

means associated with said zone for detecting the degree of non-flatness possessed by the strip in said zone, and

control means associated with said rolling pressure varying means adapted to operate said pressure varying means to vary the transverse rolling pressure in accordance with the amount of deflected non-flatness of the strip.

3. In an apparatus according to claim 2 wherein said means for controlling the rolling pressure includes means for varying the contour of the rolls to effect a change in the unit pressure across the rolls.

4. In an apparatus according to claim 3 wherein a strip deflector roll and a tension means are arranged on both sides of the mill.

5. In an apparatus according to claim 2 wherein said means for controlling the rolling pressure includes a strip deflecting roll arranged on the delivery side of said mill, between said mill and said zone and engageable by said strip,

means for creating tension between said deflector roll and said mill, and

means for varying the contour of said deflector roll to effect a change in the unit pressure across the rolls of said mill.

6. In an apparatus according to claim 2 wherein said mill includes two tandem stands each including a pair of Work rolls having supporting backup rolls,

strip deflector rolls arranged on the entry side and the delivery side, of said two stands in which said means for controlling the rolling pressure includes a first and second means,

said first means comprising force applying members engageable with the backup rolls to deflect said rolls, thereby to control the contour of the work roll, and

said second means including a force applying means engageable with said strip deflector rolls to deflect said rolls thereby to control the contour thereof.

7. In a method of controlling the flatness characteristic of metallic strip by subjecting the strip to rolling pressure created by a pair of rolls of a rolling mill or like device comprising the steps of:

reducing the thickness of the strip by rolling,

forming a zone for detecting a non-flatness condition in the strip after said rolling wherein the strip is maintained in a state relatively free of tension as it 4 passes through said zone,

detecting the presence of non-flatness in the strip when passing through said zone, varying in a controlled manner the rolling pressure transversely of the strip as the latter passes between said pair of rolls to correct for the non-flatness in the strip.

References Cited UNITED STATES PATENTS 3,006,225 10/1961 Mamas 7212 3,245,241 4/1966 Roberts 72-12 3,315,506 4/1967 Schneider 72-12 3,334,508 8/1967 Martin 72--12 FOREIGN PATENTS 6 794,290 4/1958 Great Britain.

1,469,660 1/1967 France.

CHARLES W. LANHAM, Primary Examiner G. P. CROSBY, Assistant Examiner U.S. Cl. X.R. 72-16 

